package bin_tree.oj;


class Num104 {
    public int maxDepth(TreeNode root) {
        if(root == null){
            return 0;
        }else if(root.left == null && root.right == null){
            return 1;
        }else{
            return Math.max(maxDepth(root.left),maxDepth(root.right)) + 1;
        }
    }
}


